Based on the time-domain analytical method, the wind-induced response of a simple supported beam roof structure under the downburst was studied by parameter analysis. This paper selected a hybrid stochastic model to simulate the strong wind load of downburst, where mean wind speed was simulated by the Wood vertical profile equation of wind and the Holmes’ empirical model and fluctuating wind speed was simulated by AR model based on Kaimal target spectrum. Spectral analysis results show that the simulated results of downburst have a good accuracy. This paper analyzed the influences of both main structural parameters and downburst parameters on structural wind-induced response. The results show that the stiffness, span, maximum wind speed radius and the velocity of storm moving have great influences on structural wind-induced response. Given the characteristics that both mean wind speed and fluctuating wind speed response are time-varying, this paper adopted the global wind-induced coefficient calculation method which is based on the envelope concept, where the global displacement wind-induced coefficient and the global load wind-induced coefficient under different parameters were studied respectively. The results show that adopting the structural global displacement wind-induced coefficient to calculate equivalent static wind load of downburst have a higheraccuracy.